The chairman of the U.S. House Intelligence Committee said Monday he has seen no evidence of improper contacts between officials working on President Donald Trump's campaign for the White House and Russian agents and has no plans to expand an investigation already underway.

The Republican is leading one of three congressional probes into possible links between Trump and Russians, but has balked at calls for a wider investigation.

However, the top Democrat on the intelligence panel, Congressman Adam Schiff, later said no conclusions have been reached yet on whether Trump aides had contact with Russian officials during last year's presidential campaign.

Lawmakers in both the Senate and House of Representatives are looking at details of findings by the U.S. intelligence community that Russia meddled in the U.S. presidential election in an effort to help Trump defeat Democrat Hillary Clinton, a former U.S. secretary of state.

American intelligence officials concluded that Russia hacked into the computer of Clinton's campaign chief, with the anti-secrecy group WikiLeaks later releasing thousands of emails showing embarrassing behind-the-scenes efforts by Democratic operatives to help Clinton win the Democratic presidential nomination.

Before he was inaugurated as the country's 45th president, Trump reluctantly accepted the finding that Russian President Vladimir Putin interfered with the election, but says he knows of no contacts between his campaign aides and Russian intelligence officials.

At a White House meeting with insurance company executives, Trump was asked by a reporter about demands by some lawmakers for a special prosecutor to investigate any links between his campaign and Russia.

"I haven't called Russia in 10 years," he said.

Earlier this month, National Security Adviser Michael Flynn resigned following reports he misled Vice President Mike Pence and other White House officials about his frequent contacts with Russian Ambassador Sergey Kislyak during the transition period before Trump’s inauguration.